1. Field of the Invention
The present invention relates to a living body information measuring apparatus and the like for noninvasively measuring a subject""s living body information such as the pulse rate, the blood-sugar level, subject""s subcutaneous fat thickness and fat percentage.
2. Related Art of the Invention
An apparatus for noninvasively measuring a subject""s body fat percentage has previously been proposed.
For example, U.S. Pat. No. 4,990,772 proposes a method of measuring a subject""s body fat percentage by use of near infrared rays. According to this United States Patent, near infrared rays used for ingredient analysis of food and the like are projected to a subject, and a specific wavelength component of the light having intruded into the subject is analyzed.
FIG. 45 shows the structure of a body fat percentage measuring apparatus according to the prior art. As shown in the figure, a pair of light emitting devices 12A and a light receiving device 13A are disposed on one end surface of a body 11A. In a cap 14A for protecting the end surface, an optical standard plate 15A is disposed so as to be opposed to the light emitting devices 12A and the light receiving device 13A. The light emitting devices 12A project near infrared rays to a subject being in intimate contact with the end surface of the body 11A. The projected light is reflected after intruding into the subject. The light receiving device 13A detects the reflected light. A microcomputer (not shown) incorporated in the body 11A calculates the subject""s body fat percentage based on data on the subject""s height and weight and the information on the reflected light detected by the light receiving device 13A. In the actual measurement, first, light projection and reflected light detection are performed with the cap 14A being fitted on the body 11A, and a reference value for the subsequent measurement is obtained. Thereafter, light projection to the subject and reflected light detection are performed.
However, in the above-described body fat measuring apparatus, light-shading is insufficient according to the subject""s measured part such as an arm which is thin. Light-shading is also insufficient according to the angle at which the body fat measuring apparatus is pressed against the subject. Consequently, accurate data cannot be obtained.
Moreover, since it is necessary to perform measurement twice for adjustment and for actual measurement, a long time is required for the measurement.
Moreover, since the color of the skin differs among individuals, when the color of the skin is different among subjects, the body fat percentage detected by a body fat measuring apparatus that projects light from above the skin is naturally inaccurate.
Moreover, in the conventional body fat measuring apparatus, since near infrared rays (wavelength 950 nm) are used, when the measurement is performed at a very bright place, the light having propagated through the living body becomes a disturbance because of the property of near infrared rays of more excellently passing through living bodies than visible light, so that accurate measurement cannot be performed.
Moreover, since the conventional body fat measuring apparatus uses near infrared rays which is largely absorbed by fat component, when the subject persons have different fat quality, the amount of light becomes largely changed, and Then it is difficult to detect accurately the thickness of fat.
Moreover, since the intensity of the light source and the sensitivity of the light receiving portion vary with time, it is necessary to obtain the reference value for the subsequent measurement every measurement by projecting light with the cap being fitted on the body and detecting the reflected light from the standard plate, which is very cumbersome.
Moreover, when the optical standard plate becomes dirty for some reason, the measurement value significantly differs.
Accordingly, an object of the present invention is to provide a living body information measuring apparatus and the like capable of easily obtaining living body information with high accuracy.
The present invention (corresponding to claim 1) is a living body information measuring method wherein a plurality of paths from a light emitting portion to a light receiving portion are created, and based on a light reception signal, from a path with higher accuracy, of a plurality of light reception signals obtained from the paths, living body information is calculated by a signal processor.
Moreover, the present invention (corresponding to claim 6) is a living body information measuring apparatus comprising: a light emitting portion for projecting light rays to a subject; a light receiving portion for detecting, of the light rays, a transmitted light ray having passed through the subject or a reflected light ray; and a signal processor for calculating the subject""s living body information by analyzing a light ray detected by the light receiving portion, wherein at least one of the number of light emitting portions and the number of light receiving portions is not less than two, and wherein the signal processor analyzes, of a plurality of light rays detected by the light receiving portion, a light ray with higher accuracy to calculate the subject""s living body information.
Moreover, the present invention (corresponding to claim 9) is a body fat measuring apparatus comprising: a light emitting portion for projecting light rays to a subject""s tissue; a light receiving portion for detecting, of the light rays, a transmitted light ray having passed through the subject""s tissue and/or a reflected light ray reflected inside the subject""s body; and signal processing operation means for calculating the subject""s subcutaneous fat thickness and/or body fat percentage by performing an operation by use of a detection result of the light receiving portion, wherein either the number of light emitting portions or the number of light receiving portions is not less than two, and wherein the not less than two light emitting portions or light receiving portions are situated at different distances from corresponding light receiving portion or light emitting means.
Moreover, the present invention (corresponding to claim 20) is a body fat measuring method using a body fat measuring apparatus of the present invention, said body fat measuring method comprising the steps of: projecting light rays to the subject by the light emitting portion; detecting a transmitted light ray (and/or a reflected light ray) having arrived by way of the subject""s skin or skin and a layer in the vicinity thereof by the first light receiving portion; detecting a transmitted light ray (and/or a reflected light ray)having arrived by way of the subject""s skin and subcutaneous fat layer by the second light receiving portion; and calculating the subject""s subcutaneous fat thickness or body fat percentage by the signal processing operation means by correcting a detection result of the second light receiving portion by a detection result of the first light receiving portion and performing an operation by use of a result of the correction.
Moreover, the present invention (corresponding to claim 21) is a body fat measuring method using a body fat measuring apparatus of the present invention, said body fat measuring method comprising: a step in which a light ray projected by the first light emitting portion is detected by the light receiving portion as a first transmitted light ray (and/or a reflected light ray)having passed through the subject""s skin or skin and a layer in the vicinity thereof; a step in which a light ray projected by the second light emitting portion is detected by the light receiving portion as a second transmitted light ray (and/or a reflected light ray)having passed through the subject""s skin and subcutaneous fat layer; and a step in which the subject""s subcutaneous fat thickness or body fat percentage is calculated by the signal processing operation means by correcting a detection result obtained by the second light emitting portion and the light receiving portion by a detection result obtained by the first light emitting portion and the light receiving portion and performing an operation by use of a result of the correction.
The body fat measuring apparatus of the present invention as described above is provided with a light emitting portion for projecting light rays to the subject, a light receiving portion for detecting, of the light rays, a transmitted light ray having passed through the subject or a reflected light ray, and a signal processor for calculating the subject""s living body information by analyzing the light detected by the light receiving portion. Two or more light receiving portions or light emitting portions are provided, and the body fat is calculated by use of a measurement value from the light receiving portions. Further, it is desirable to use a light emitting diode with a central wavelength of not more than 650 nm as the light emitting portion.
Moreover, the present invention (corresponding to claim 22) is a living body information measuring apparatus comprising: a light emitting portion for projecting light rays to a subject""s tissue; a light receiving portion for detecting, of the light rays, a transmitted light ray having passed through the subject""s tissue and/or a reflected light ray reflected inside the subject""s body; and signal processing operation means for calculating the subject""s living body information by performing an operation by use of a detection result of the light receiving portion, wherein either the number of light emitting portions or the number of light receiving portions is not less than two, wherein the not less than two light emitting portions or light receiving portions are situated at different distances from corresponding light receiving portion or light emitting portions, wherein light sources of the plurality of light emitting portions are the same, or photoelectric conversion devices of the plurality of light receiving portions are the same, and wherein one of outputs of the plurality of light emitting portions or outputs of the plurality of light receiving portions is corrected by another one of the outputs.